Small Engines (Lawn Mowers, etc.): 31 cc two cycle, leaf blower, piston

Question
I have cleaned the engine on a leaf blower and upon re assembly found that the engine ran for about 30 min and then lost all compression, after inspecting the piston i found that it was burnt badly so I replaced the rings and it did the same thing, ran fine for about 30 - 45 min then lost all compression again burning another set of rings.  what do you suspect may be the issue

Answer
Did you replace the cylinder as well?  Re-ringing a two-stroke without replacing the cylinder is pretty much not going to be successful most of the time.  You could also have a poor seal at the crank seals, but if you didn't replace the cylinder, I'd think that would be the cause.  thanks, PK.